sabato 31 maggio 2008

Is sex necessary for reproduction?

Dr. Mark Hughes likes to startle audiences by declaring that sex may become outdated as a means of human reproduction. His field will replace it with technology, he submits."It is going to be, 'Sex is just for fun,' " Hughes will tell a crowd. "In vitro fertilization is going to be for making your children."Hughes is joking - for the most part. But as head of a major embryo-screening company, Genesis Genetics Institute in Detroit, he also makes a compelling business argument that sex is in for some serious competition from assisted reproductive techniques.By conceiving a child outside the womb, he says, parents gain the power to erase a hereditary disease from their family lineage. His company plucks a single cell from each of the embryos created for clients at in vitro fertilization clinics. After genetic testing of the sample cells, only the embryos found free of the disease gene are implanted to cause a pregnancy.As the harvest of human genome studies continues, Hughes said, many more diagnostic tests for such genetic vulnerabilities are being developed. "The numbers of diseases we can do are just exploding," he said.Pre-implantation genetic screening is just one of the offerings that can motivate even fertile individuals to make conception an affair surrounded by beakers and microscopes, rather than moonlight and roses.The in vitro fertilization industry, which originated in the 1980s as a solution for infertile couples, has actively sought to expand its market scope by tapping social trends and collaborating with researchers in genetics and stem cell technology.Assisted reproduction clinics have welcomed gay men, lesbians and older women who want to become parents. At some clinics, young women can freeze their eggs to boost the chance of a healthy child if they delay childbirth while building a career or searching for a soul mate. Some embryo-testing centers, though not Hughes' company, will help parents choose the gender of their child.Genesis Genetics helped pioneer an avenue for parents who want a baby born with the right genetic traits to serve as a tissue or cell donor for a desperately ill brother or sister. Hughes calls this the "Save Your Siblings" technology. If the parents conceive in vitro, Genesis Genetics can pick the embryo that is most compatible with the ill sibling and reduce the danger of immune system rejection.Beyond those developments, in vitro fertilization and stem cell technology are advancing in tandem. Researchers who see embryonic stem cells as possible future remedies for spinal cord injuries and degenerative diseases look to clinics for donations of surplus embryos from clients who have already completed their families. Now a stem cell company, StemLifeLine of San Carlos, is offering in vitro clients an additional service.

Stem cell line:The company will convert the parents' extra embryos into a stem cell line for the family, on the chance that the cells might contribute to a future treatment for one of its members. Donor cells from surplus embryos might lower the risk that a related family member would suffer an immune system reaction, the company says. Critics are skeptical of the benefits, and some worry that parents will feel obligated to create a stem cell line for the family.In fact, most of the new uses for in vitro fertilization have raised ethical or practical concerns. Technologies surrounding the birth of an individual lead to core questions about identity and familial responsibilities.Even the advocates of assisted reproduction say it's hard for society to adjust its ethical frameworks to keep up with research developments. "The technologies are coming at a breakneck pace," said Anne Adams, a spokeswoman for the American Fertility Association, an advocacy group for in vitro clients.Writers have been quick to predict drastic changes in society as new reproductive feats emerge from labs. One pivotal event was the birth in 1996 of the first cloned mammal, Dolly the sheep, who was conceived in a laboratory from only one parent, her mother. Soon after that, scholars posed the question "Is Sex Obsolete?" in a book about cloning.The 1997 film "Gattaca" presented a cautionary vision of a future world in which few humans were conceived the old-fashioned way because it left the outcome up to a chance reshuffling of the parents' genes. Instead, genetically enhanced embryos were conceived in vitro. In the filmmaker's tale, society discriminated fiercely against people who were the natural products of "faith births."So far, though, conceiving the traditional way is holding its ground. In vitro fertilization is expensive, and requires a woman to undergo hormone injections and a procedure to extract egg cells.However, the number of births from assisted reproduction in the United States doubled between 1996 and 2005 to more than 52,000. Those infants made up 1 percent of the babies born in the United States in 2005, according to the unit that compiles the data for the U.S. Centers for Disease Control and Prevention.The numbers for more recent years aren't yet available. Neither the CDC nor industry groups have been tracking the reasons parents chose in vitro fertilization, so it's hard to say whether its use is growing for reasons other than infertility.

Raising alarms:The rapid pace of discoveries in reproductive medicine, however, is raising alarms among watchdog groups who fear the lightly regulated industry will reshape parenthood and culture before society has the chance to evaluate the new techniques. Defenders of the research, on the other hand, say the groups are unnecessarily concerned about recent work intended to develop embryonic stem cell lines for studies of disease.Within the past nine months, groundbreaking advances have emerged with help from assisted reproduction companies. Stemagen Inc. of La Jolla (San Diego County) reported it had cloned human embryos from adult skin cells, using eggs donated by clients of the La Jolla branch of an in vitro fertilization consortium, the Reproductive Sciences Center. Genesis Genetics verified that the cells were clones.Researchers at the Weill Medical College of Cornell University recently confirmed that they had genetically modified human embryos by inserting extra genes. Cells derived from cloned or modified embryos can be used to illuminate disease processes and test possible treatments. The scientists did not induce the embryos to develop into fetuses.Early this year, Advanced Cell Technology of Los Angeles said it had derived stem cell lines from embryos without destroying those embryos, a step hailed because it might overcome ethical objections to embryonic stem cell research. But in addition, one of the research partners, StemLifeLine, said it hopes it can soon offer in vitro clinic clients the chance to have a stem cell line made that is an exact genetic match to their babies.Cornell's foray into genetic engineering of human embryos caused an uproar among watchdog groups such as the Center for Genetics and Society in Oakland.Marcy Darnovsky, associate executive director of the group, said the Cornell work should not have been done without a broad public policy debate. Whatever its intent, Darnovsky said, the research could help create the technological foundations for "a real-world Gattaca" of genetically enhanced offspring for the affluent and discrimination against unenhanced genetic castes."The technology and also the market dynamics are developing really quickly here," she said. "We don't want to be on the platform watching the train pull out of the station."Hughes said genetic enhancement of children by adding genes to an embryo may not be feasible for many years, if ever. The technical challenges alone would be formidable, he said.

Favorable genes:Similarly, enhancing favorable traits may not be possible by screening embryos conceived through in vitro fertilization, he said. Most desirable traits, such as intelligence, are the products of many different genes, he said. Parents would have to create large numbers of embryos to produce a single one with all the favorable genes, he said.But Hughes said he does think that many more people will turn to assisted reproduction because of technology that is already in place - the use of embryo screening to eliminate genetic diseases.For one thing, Hughes said, people are becoming much more aware of their familial disease risk as more genetic tests become available. And parents in the United States are having fewer children later in life, he said. They'll want less risk with the few they have, Hughes predicted. "They're going to use medical technology to at least stack the deck in favor of a healthy child."But Hughes is also betting that his specialty - pre-implantation genetic screening - will become obsolete before sex does."I think we will hopefully find cures for these conditions and we won't have to avoid them," he said.

Fertilization timeline:In vitro fertilization and other assisted reproductive techniques have tackled infertility and inherited disease, but advances in the technology have raised fears of sexless societies of genetically engineered children.1932: "Brave New World" by Aldous Huxley published. Huxley's dark novel envisions the elimination of natural reproduction by a society that uses technology to produce humans divided into upper and lower classes or "genetic castes."1960: Food and Drug Administration approves birth-control pills.1970s: Emergence of commercial artificial insemination services.1978: In vitro fertilization. The first test-tube baby, Louise Brown, born in England.1989: Pre-implantation genetic screening. The first births of children from embryos screened to eliminate disease genes.1996: First cloned mammal, Dolly the sheep, is born.1997: "Gattaca" released. Filmmaker Andrew Niccol presents a future society in which sexual reproduction is nearly obsolete, and genetically enhanced humans discriminate against those with inherited limitations.2000: Embryo screening for child tissue donor. The first baby is born from an embryo selected because he was a genetic match to an ill sibling who needed a tissue donation.2005-06: Egg freezing. A growing number of clinics offer to freeze eggs for women who postpone childbirth.2007: Genetically modified human embryo. Cornell scientists report they have inserted genes into a human embryo in order to derive stem cells for disease research.January: Advanced Cell Technology of Los Angeles says it has derived stem cell lines from embryos without destroying the embryos.Stemagen Inc. of La Jolla reports it has cloned a human embryo from a skin cell, in order to derive stem cells for disease research.